The present invention relates to the general technical field of agricultural machinery. The invention concerns an agricultural machine for working the soil or for sowing seeds, with a trailed chassis and work elements distributed on a longitudinal bar in several sections, the longitudinal bar has at least two primary beams extending substantially transversely to the direction of advance in a work configuration.
In the case of a seeding machine or a seeder, the work elements rest on the ground with a predetermined pressure or must work the soil at a specified depth to ensure a good germination of the seeds and a homogeneous emergence of the plants. In the case of a machine for working the soil or for preparing a seedbed, the work elements, in the form of teeth or discs, must work at a specified work depth.
Such a machine for sowing seeds is represented in the document U.S. Pat. No. 8,001,914 B2. This agricultural machine has a trailed chassis with a longitudinal bar in two sections. The longitudinal bar thus has two primary beams carrying work elements. This is a single seeder having a large width, the work elements of which deposit the seeds at a specified depth in furrows. Each primary beam is directed transversely to the direction of advance and is connected to the chassis via an articulation having an axis which is substantially horizontal and parallel to the direction of advance. The free end of the primary beam rests on the soil via a support wheel. Each section pivots upwards or downwards about the articulation having a horizontal axis according to the surface traced by the support wheel situated at the end. Thus, only the work elements situated directly in the vicinity of the support wheel will have a precise position with respect to the soil observing the desired work depth. The other work elements, more distant from the support wheel, will follow the undulations of the terrain more roughly, and the planting depth of the seeds will not be homogeneous over the entire length of the primary beam. It is noted, moreover, that the support wheel extends at the front of the primary beam, whereas the work elements are arranged at the rear. This distance between the support wheel and the work elements, taking into account the direction of advance, also causes a loss of precision for the work elements with regard to their following of the terrain. The same applies for the work elements arranged towards the centre, since the wheels carrying out the control of the depth are remote from the work elements, because they are fastened at the rear of the chassis.